Physiology &f ILematopinus tenuirostris, Barm. 99 



by the various authors, although we almost always find the 

 nits on animals on which the lice are parasitic. It is true 

 that these escape the eye more easily than the lice themselves, 

 as they often mimic the colour of the hair or of the skin of the 

 host. Denny alone gives figures of the eggs of Ha matopinus 

 lyriocephalus, Burrn., and H. eurysternus, Nitzsch. And yet 

 the eggs, with their operculum, their micropylar apparatus, 

 and the mode of their attachment, are of no small importance, 

 both as regards the internal anatomy and developmental history 

 and as regards classification. 



Male Generative Organs. 



The male sexual organs include the testes, the mucus-organs, 

 and the penis. 



The testes, as in all Lice hitherto investigated, are four in 

 number ; and each pair has an efferent duct. They are situated 

 on the two sides of the body, at a considerable distance apart, 

 and are of an oval form. Their width is 0*154, and their 

 length 0"247 millim. The whole testis is surrounded by a 

 pretty firm structureless membrane. Superiorly this passes 

 into a thin thread-like vessel of 0*013 millim. width, with 

 a fine lumen and pale yellow contents, which connects the 

 testis with the vas dorsal e. Diametrically opposite to this 

 point the envelope of the testis lengthens out to form the 

 seminal duct, which is 0'048 millim. wide and very long. The 

 two testes are situated quite close together ; both are attached 

 without any peduncle to the end of the seminal duct The 

 latter presents a fine textureless membrane, a small lumen, 

 and clear granular contents. Its length is considerable, 

 equalling that of the abdomen. The seminal elements, deve- 

 loped in the testes, consist of a rounded head and a long thin 

 caudal part. As regards the development of the spermato- 

 zoids I can at present say nothing, as only a few males of our 

 animal were at my disposal during the investigation. 



Between the seminal ducts are placed the mucus-organs, 

 two large structures, 0*340 millim. broad, which exhibit a 

 structureless outer envelope and contents consisting of gland- 

 cells. Below these organs contract into efferent ducts, which 

 cross a little way from their point of union, so that the efferent 

 duct of the right mucus-organ approaches that of the left one 

 from the left, and vice versa. A little before they unite 

 these structures receive the two seminal ducts. 



T\ie penis \§ a bacilliform strongly muscular organ 0- 186 

 millim. long and - 049 millim. broad, into which strong 

 chitinous bands are inserted at the sides. The latter run into 

 four chitinous rods, which attain the length of the penis. 



